The "Listen" button is located in between the "Like" and "Message" buttons on the artist's page and will connect the user to the music service that they use most often. The very first time you click on the "Listen" button, a notice from the resulting participating service will pop up and ask you to grant access. If you will to listen to music you will have to accept this access.
All your listening activity will be published to your page in real-time since the music service apps are connected with the Facebook Timeline.
Will you be using Facebook to listen to your favourite artists? Do you think Facebook will be introducing more music orientated tools onto their social media network in the future? Let us know your thoughts.